Field of the Invention
The present invention relates to a technique for acquiring captured image signals for stereoscopic vision, and generating image signals.
Description of the Related Art
In recent years, stereoscopic images and stereoscopic image-related devices such as 3D movies and 3D displays have rapidly prevailed. Capturing of stereoscopic images is conventionally done using a film camera or the like. However, along with the popularization of digital image capture apparatuses such as digital cameras and digital video cameras, images as generation sources of stereoscopic images are captured using these digital image capture apparatuses.
The following mechanism for appreciating stereoscopic images is generally used. That is, “right-eye image” and “left-eye image” having a parallax in a right-and-left direction are prepared in correspondence with an image when the user views an object by the right eye and that when he or she views it by the left eye, and the user views the “right-eye image” by the right eye and the “left-eye image” by the left eye. As this method, a method of dividing an image to be appreciated to have a parallax using a parallax barrier system, lenticular system, or the like, and a method of controlling different images to become incident on the right and left eyes via right and left filters having different characteristics are known.
As an image capture method of images which can be appreciated as stereoscopic images, a method of simultaneously capturing images at different view points is available.
In a solid state image sensor described in Japanese Patent Laid-Open No. 58-24105, a plurality of microlenses are formed on the solid state image sensor, and at least a pair of photodiodes are disposed in the vicinity of each of these plurality of microlenses. A first image signal is obtained from an output of one photodiode of this photodiode pair, and a second image signal is obtained from the other photodiode. As described in Japanese Patent Laid-Open No. 58-24105, when the first and second image signals obtained in this way are used as the “right-eye image” and “left-eye image” described above, stereoscopic images can be appreciated.
A solid state image sensor described in Japanese Patent Laid-Open No. 2007-325139 has an arrangement in which a plurality of microlenses are also formed on the solid state image sensor, and a plurality of photodiodes are disposed for each microlens. As a characteristic arrangement of Japanese Patent Laid-Open No. 2007-325139, the plurality of photodiodes which are disposed in correspondence with one microlens are connected to each other via gates. Therefore, whether signals of the neighboring photodiodes are to be added in a pixel or they are read out without being added can be controlled.
Japanese Patent Laid-Open No. 2007-325139 obtains captured image signals and focus detection signals of an image capture apparatus using the solid state image sensor with the aforementioned arrangement. In a normal image capture mode, signals of all photodiodes are added to generate captured image signals. In a focus detection mode, signals having a parallax have to be obtained. In order to obtain signals having a parallax in the right-and-left direction, photodiodes, which neighbor in an up-and-down direction, need only be connected. Also, in order to obtain signals having a parallax in the up-and-down direction, photodiodes, which neighbor in the right-and-left direction, need only be connected. Japanese Patent Laid-Open No. 2007-325139 presents the following use method. That is, using the solid state image sensor with this arrangement, accurate focus detection is attained using combinations of addition results of the photodiodes, which are suited to focus detection of an object image, in accordance with the pattern of the object image.
Image signals generated by an image capture apparatus are normally printed on media such as paper or are displayed on a display device such as a television, monitor, or projector when they are appreciated. The same applies to 2D images and 3D images.
In order to appreciate stereoscopic images, as described above, the user has to view images having a parallax in the right-and-left direction by the corresponding eyes. Therefore, in all the systems described in the related art, the “right-eye image” to be appreciated by the right eye and the “left-eye image” to be appreciated by the left eye have to be prepared.
The related art literatures explain the solid state image sensor having the arrangement in which the plurality of microlenses are formed on the solid state image sensor, and a plurality of photodiodes are disposed for each microlens. Also, as described in these literatures, a plurality of captured image signals, which can be respectively used as the “right-eye image” and “left-eye image” displayable as stereoscopic images, can be obtained using the solid state image sensor with such arrangement.
However, with the inventions described in the related art literatures, although the “right-eye image” and “left-eye image” can be obtained, a parallax between the “right-eye image” and “left-eye image” often has a direction that does not allow these images to be appreciated as stereoscopic images.
That is, in the technique described in Japanese Patent Laid-Open No. 58-24105, the layout of photodiode pairs at the time of design decides, in advance, the direction of a parallax of captured images.
Or in the technique described in Japanese Patent Laid-Open No. 2007-325139, the direction of a parallax of captured images is decided by combinations of addition results of photodiodes, which are selected according to an object image, when signals are read out from the photodiodes. That is, the “right-eye image” and “left-eye image”, which are generated from signals read out from an image capture apparatus, can have only a parallax in one direction, which is decided in advance before signals are read out.
Therefore, when the parallax direction of images does not match that of the two eyes of the user upon appreciating captured images, the user cannot recognize these images as stereoscopic images. For example, when images having a parallax in the right-and-left direction are displayed while being rotated through 90° from a normal position, the parallax direction of the two images changes from the right-and-left direction to the up-and-down direction, and these images cannot be appreciated as stereoscopic images, thus posing a problem.